The proposed work continues studies on the neurosecretory hormones of the crustacean eyestalk. The recent description of molecular differences in the hyperglycemic ("diabetogenic") hormone among three crustacean species is based on differences in response obtained in cross-injection experiments, differences in elution volumes from anion exchange columns and differences in mobility in gel electrophoresis, among three species. Efforts are now being concentrated on the preparation of hormone from the eyestalks of two species (possibly three species, if eyestalks of the third species can be obtained in adequate amounts) in sufficiently pure form for comparison of their amino acid composition (and sequence?) as the possible difference for the observed results. The purified preparations will also be tested for their specificity in other physiological responses effected by eyestalk extract. In addition, studies are progressing on the purification of another pigmentary-effector hormone (one which concentrates pigment in leucophores) and in a partially-purified factor which can be regarded as an uncoupling agent of oxidative phosphorylation, since it has been found to stimulate succinate oxidation in intact mitochondria.